This invention relates to a composition for cleaning contact lenses. The composition comprises an aliphatic monohydric alcohol, a surface active material having cleaning action for contact lens deposits, and an abrasive agent.
The tendency of contact lens materials to form deposits necessitates regular cleaning of the contact lenses. Deposits from the tear film include protein, lipid and mucin, and deposits from external sources include cosmetic deposits, such as from mascara or hair spray, or materials deposited when the lens is handled.
Enzymatic contact lens cleaners are frequently used to remove protein deposits, especially denatured proteins, particularly with hydrophilic soft contact lenses for which protein is the major deposit problem. However, enzymatic cleaners are not particularly effective for other types of deposits.
Surfactant contact lens cleaners, which employ a surface active agent having cleaning action, are used to remove lipid deposits, loosely bound protein deposits, and other deposits. Surfactant cleaners are used in conjunction with finger rubbing or other mechanical cleaning, followed by rinsing to remove the deposits. Surfactant cleaners are used for hard and soft contact lenses. Hard lenses include polymethylmethacrylate lenses and rigid gas permeable lenses formed of a silicon acrylate or a fluorosilicon acrylate polymer. Soft lenses include hydrophilic hydrogel lenses.
Various surfactant contact lens cleaners which employ an alcohol, such as ethanol or isopropanol, are known. A commercial product marketed by CIBA Vision (Atlanta, Ga., USA) as an "extra-strength" contact lens cleaner is MiraFlow.RTM. Extra-Strength Daily Cleaner. This cleaner includes, as principal active ingredients: isopropanol; poloxamer 407 (a polyoxyethylene, polyoxypropylene block copolymer such as available under the trade name Pluronic F-127); and an amphoteric imidazole surfactant. Similar compositions are disclosed in U.S. Pat. No. 4,046,706 (Krezanoski).
Additionally, U.S. Pat. No. 4,421,665 (Lloyd et al.) discloses alcohol-containing contact lens cleaning solutions comprising: a non-polar solvent in the form of cyclohexane and/or ethyl acetate, and optionally. trace amounts of chloroform; ethanol or isopropanol as a polar solvent; and a surfactant. The surfactant is preferably a nonionic surfactant, although dioctylsulfosuccinate is also disclosed. The patent discloses that the non-polar solvent is adapted to provide for enhanced solubility of lipids and lipoproteins, and the alcohol has the ability to dissolve fully the non-polar solvents and potentiate their anti-microbial activity. However, the use of non-polar solvents such as cyclohexane, ethyl acetate, and chloroform in a contact lens solution is undesirable in case the composition is not adequately rinsed from the lens.
A challenge is to develop alcohol-containing contact lens cleaning compositions which not only provide the desired cleaning efficacy, but which also are suitable for ophthalmic use and are less damaging to the lenses. Efforts to develop alcohol-containing contact lens cleaning compositions often lead to compositions which damage the lens; for example, use of the compositions in a cleaning regimen may result in scratching of the lens surfaces, or deterioration of the lens such that the power of the lens is changed.